Ways to reinforce basement steel beams

[Tdog67]

Fellers,

I am exploring all the different ways i can eliminate an interior post supporting a multi-span W8x18 beam in my basement. I've looked at placing a HSS 5x2 inside the web and adding a plate to the bottom. On one side of the beam is the supply duct so i can only get to one side or just the bottom flange. What unique ways have you seen a beam like this reinforced. I'm also inquiring for any future reference work.

thanks

 

[MiketheEngineer]

I have simply added a beam to one or both sides with additional posts. You might have to beef up the footing.

Usually you can "frame" out the posts and just make them look like a big column??

 

[kslee1000]

If you don't have problem with head room, attach the HSS to the bottom would be more effective, and less troubles. You would need to check end bearing and shears.

Do you need to open up the entire bay? Can you move the post somewhere along (relocate) the beam if it is in the way of something.

 

[Lion06]

How much room do you have below the beam? A WT is the most efficient way to go as this gives you the most bang for your buck in terms of I (and deflection will likely be an issue going from a two span condition to a simple span of double the length). You probably want to look at vibrations for this as well as the footings/walls as suggested above.

 

[Tdog67]

These ideas are the usual way we would use in commercial or industrial projects. I'm looking for more ideas so i don't have to shore up the floor joists to take out the middle column first. Headroom is also critical so i want to avoid going much deeper than what the W8 is now. I'm also looking for ideas for future work with homeowners who want to do the same thing.

thanks

 

[kslee1000]

Engineering principles are the same regardless of type of use of BUILDINGs. Your original thinking was flawed, the latter is difficult if not impossible (more knowledge on the floor system/layout is required). I can only think one thing you can do a guarded check before all others is to check the live load on the existing beams, which could be down to zero during demo. What else is on the existing beams? Can you remove it prior to do something below...I think you need to provide more info in order to get positive responses.

 

[PEinc]

If there were a good, easy way to beef up a basement beam so that we could remove a column, we we could get rich. IMHO, I don't think anyone's found a good, easy way.

 

[Lion06]

Here's the problem with "not going much deeper" - Assuming the post is halfway between the end supports and each segment has a length, L, then the negative moment at the post is wl^2/8. If you take out the post and make it a single, simple span, the positive moment is now 4wl^2/8, or wl^2/2 - You've increased the moment by a factor of 4. I understand that you will get some benefit by having positive moment instead of negative moment, but it's difficult to increase your capacity that much without "going much deeper" and ever harder to increase your I by that much (which doesn't care about M+ or M-.

 

[msquared48]

Can't do much as with the top flange, but what about adding a channel, legs up, to the bottom flamge to increase the S and I?

For the tearing on the op flange, you could add two angles, legs down, one either side, assuming the bottom of the joists are bearing on the top of the wideflange.

Percentage wise, how much do you have to increase the existing S and I to get the beam to work?

Mike McCann
MMC Engineering

 

[slickdeals]

Here is a thought...

How about adding 2 MC channels and welding continuously to the bottom flange on either side of the web? You can add intermediate stitch plates connecting the MC's and notch around the post if needed. Maybe this will give you enough depth to remove the column without shoring.

-------
|
|
-- | --
|------|
| | <--- MC Welded to bottom flange
| |
-- --
-------- Stitch Plate

 

[Tdog67]

kslee,

my thinking was not flawed (I see you are civil/environmental), i've done this numerous times. I'm just looking for a way that most people wouldn't come up with. I'm basically trying to keep the reinforcing with the web of the beam. i've looked at adding tube sections, channels, plates, etc. It seems the most efficient is adding a plate to the bottom of the flange to maximize headroom but there is the issue with having to remove the column to keep the plate continuous or working around the column before cutting it away. I'm looking for efficiency and reduced labor expense of having to shore the joists on each side. I'm also limited by having a supply duct right next to one side of the W8x18 beam.

T

 

[kslee1000]

StructuralEIT has done a preliminary cal for you. On top of increased load, even the 2x5 HSS is good for shear and bending stresses, how about deflection and torsion? You have introduced at least 1" eccentricity, not to mention the gaps on top & bottom of the HSS. I am glad I am a civil/env that don't have to deal with this mess. Good luck.
(One more reminder, you may not gain much benefit by adding cover plate on bottom flange without some strengthening on top)